The users of cartons as disclosed and claimed herein often have different criteria for how their products are best presented in the marketplace. This criteria may include shape, size and how the carton is to be opened for use. The object is to make cartons of a particular user unique and different from the cartons of its competitor to achieve brand recognition. For these reasons, the manufacturers of such cartons must maintain a number of cutting dies on hand for die cutting and printing the various carton designs requested.
In recent years, many carton users have settled upon a fundamental tray design for such cartons which is known in the trade as a Sprinter tray. The Sprinter tray is used for entrees, vegetables, desserts and the like. The tray is generally formed in the shape of a rectangle with two side walls and two ends walls connected to a bottom wall. The corners of the tray (i.e., the adjacent ends of the respective end and side walls), are connected together by full height gusset panels to make the tray substantially liquid tight. Each of the side and end walls are provided with flanges at their upper edges and at least one of the gusset panels at each corner includes a flange portion which is bonded to overlapping extensions of the side and end wall flanges when the tray is formed. During the tray formation, the gusset panels at each corner are also bonded together and folded for bonding to an end or side wall. A lid is provided for the tray which fully overlaps the tray flange and is bonded thereto after the tray is filled. The lid may be separate from the tray or may be integral with the tray, in which case a flange may be omitted along the side of the tray to which the lid is attached. Nevertheless, despite settling upon a fundamental tray design, users still want their cartons to standout in the marketplace.
To achieve this result, some users specify that their cartons open by removing the lid in a left-to-right motion, while others specify a right-to-left opening scheme. In order to accommodate both such users while minimizing the number of dies which must be purchased and maintained by the manufacturer, the present invention was developed.
The most fundamental means for venting and opening cartons of the type disclosed herein has been the simple use of a knife or other sharp object for cutting the lid. Many such cartons include dotted lines printed on the lid surface indicating where the lid can be cut. However, this has not proven to be a completely satisfactory method and a number of alternatives have been developed. In any scheme for opening such cartons, where the lid is removed, the lid must either de-bond to the flange, or a portion of the flange must de-bond to the lid. U.S. Pat. No. 4,183,458 discloses such a technique where either the tray o the lid is applied with cut lines for breaking away when the carton is opened. Other U.S. patents which disclose related venting and opening schemes include U.S. Pat. Nos. 4,871,071 and 4,955,530 where the venting and opening scheme is applied only to the lid at one corner. In addition, the applicant herein has two pending patent applications (U.S. application Ser. Nos. 07/831,991 and 07/925,745) which disclose structures related to the present invention. The prior art opening and venting schemes are each satisfactory to some extent, but they fail to address the problem solved by the present invention.